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Message-Id: <1244385405.5265.7.camel@subratamodak.linux.ibm.com>
Date: Sun, 07 Jun 2009 20:06:45 +0530
From: Subrata Modak <subrata@...ux.vnet.ibm.com>
To: fmhess@...rs.sourceforge.net
Cc: Greg KH <greg@...ah.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Ian Abbott <abbotti@....co.uk>,
David Miller <davem@...emloft.net>, sachinp@...ux.vnet.ibm.com,
sfr@...b.auug.org.au, linux-kernel@...r.kernel.org,
Linuxppc-dev@...abs.org, linux-next@...r.kernel.org,
paulus@...ba.org, Geert.Uytterhoeven@...ycom.com,
geert@...ux-m68k.org
Subject: Re: [BUILD FAILURE 01/04] Next June 04:PPC64 randconfig
[drivers/staging/comedi/drivers.o]
On Sat, 2009-06-06 at 09:36 -0400, Frank Mori Hess wrote:
> On Saturday 06 June 2009, Greg KH wrote:
> > Frank and Ian, any thoughts about the vmap call in the
> > comedi_buf_alloc() call? Why is it using PAGE_KERNEL_NOCACHE, and what
> > is the prealloc_buf buffer used for?
>
> It is a circular buffer used to hold data streaming either to or from a
> board (for example when producing an analog output waveform). Reads and
> writes to the device files read/write to the circular buffer, plus a few
> drivers do dma directly to/from it. I personally don't have a problem
> with requiring drivers to have their own dma buffers and making them copy
> data between their private dma buffers and the main circular buffer. I
> guess the original design wanted to support zero-copy dma.
Great to hear that. How about a patch that solves my build problem on
PPC64(the problem seems to be existing for long) ?
Regards--
Subrata
>
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